Process for vulcanizing polyepihalo-hydrin rubbers

ABSTRACT

NEW PROCESS FOR VULCANIZING POLYEPIHALOHYDRIN RUBBERS BY HEATING IN THE PRESENCE OF TRITHIOCYANURIC ACID AND/OR ITS DERIVATIVE SUCH AS SODIUM TRITHIOCYANURTE. THE VULCANZIED PRODUCT HAS EXCELLENT AGING STABILITY, ESPECIALLY GOOD STRENGTH AT BREAK AFTER AGING. VULCANIZED POLYEPIHALOHYDRIN RUBBERS CONCURRENTLY HAVING ENHANCED OXIDATION-PREVENTING PROPERTIES CAN BE OBTAINED BY PERFORRMING THE VULCANIZATION IN THE CO-PRESENCE OF A 2-MERCAPTOIMIDAZOLINE SUCH AS 2-MERCAPTONIMIDAZOLINE, OR A CARBAMATE OF A POLYAMINE SUCH AS HEXAMETHYLENEDIAMINE CARBAMATE.

United States Patent 3,787,376 PROCESS FOR VULCANIZING POLYEPIHALO- HYDRIN RUBBERS Yoshiro Nakamura, Iwate, and Rikio Nagatomi, Tokyo, Japan, assiguors to Nippon Zeon Co., Ltd., Tokyo, Japan No Drawing. Filed Jan. 3, 1972, Ser. No. 215,106 Claims priority, application Japan, Dec. 31, 1970, 46/123,524, 46/ 123,525 Int. Cl. C08g 23/00 US. Cl. 260-79 17 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a novel process for vulcanizing polyepihalohydrin rubbers. More specifically, the invention relates to a process for vulcanizing polyepihalohydrin rubbers by heating a polyepihalohydrin rubber in the presence of trithiocyanuric acid and/or its derivative, or in the presence of (a) trithiocyanuric acid or its derivative and (b) a Z-mercaptoimidazoline or a carbamate of a polyamine.

It has already been known that trithiocyanuric acid or its derivative proves effective as a vulcanization accelerator in the sulfur vulcanization of diene-type rubbers (see British Pat. 1,095,219), and as an anti-oxidant for dienetype rubbers (see U.S. Pat. 3,240,749).

It is an object of this invention to provide a new and useful process for vulcanizing polyepihalohydrin rubbers in the presence of trithiocyanuric acid and/or its derivative, thereby to give vulcanized products of far superior solvent resistance and resistance to aging under heat to those attained with the conventional techniques.

Another object of this invention is to provide a new and useful process for vulcanizing polyepihalohydrin rubbers in the presence of trithiocyanuric acid or its derivative, and a Z-mercaptoimidazoline or a carbamate of a polyarnine, thereby to give polyepihalohydrin vulcanized products of such properties which further possess outstanding oxidation-preventing properties.

According to the invention, a cross-linked chain containing a triazine ring is formed by heating trithiocyanuric acid or its derivative with the side-chain halogen of a polyepihalohydrin rubber which has reactivity essentially different from that of the diene-type rubber, and its oxidation-preventing efiect is utilized.

The trithiocyanuric acid or its derivatives used in the present invention are compounds having the following General Formula I, II, III, IV, or V.

"ice

(III) I SR2 In these formulae, R is H or an alkali metal; R is H, an alkali metal, 'C H or C H R is H, C H C6H5, 'CGHH (Cyclohexyl), CH2CH=CH2, 0r CloHs (naphthyl); R is C H N(CH O (morpholino), N(CH (piperazino), or C H (naphthyl); Q is OC H O, OCH (CH OCH ),,CH O, SC H S, or SCH (CI-I OCH ,CH S; and n is a positive integer.

Typical examples of these compounds include trithiocyanuric acid and its alkali metal salts, and 2-(n-octylthio)-4,6-dirnercapto-s-triazine or its alkali metal salts, which correspond to Formula I; 2-diphenylamino-l,6-dimercapto-s-triazine, 2 diethylamino-4,6-dimerca-pto-s-triazine, 2-naphthylamino-4,6-dimercapt0-s-triazine, and 2- anilino-4,6-dimercapto-s-triazine, and alkali metal salts of these, which correspond to Formula II; 2-phenoxy-4,6-di mercapto s triazine, 2 ethoxy 4,6 dimercapto-striazine, and alkali metal salts of these, which correspond to Formula III; 2 phenyl 4,6 dimercapto s triazine, 2 morpholino 4,6 dimercapto s triazine, 2-piperizyl- 4,6 dimercapto s triazine, and alkali metal salts of these, which correspond to Formula IV; and 6-(diethylene glycol dithio)-2,4 bis(dimercapto) s triazine and its alkali metal salts, which correspond to Formula V.

Of these compounds, the alkali metal salts generally have the greatest reactivity with the side-chain halogen of a polyepihalohydrin rubber. The reactivities of some typical alkali metal salts increase in the order shown below.

(EllJNa ZOuHs Z0 5 i t r f r r r NaS-C O-SNa NaS-C C-SNa NaS-C C-SNa N N N Cgils CaHa Ca ais /C2Hs t t I NaS-C CSNa NaSO 0-SNa Of those compounds which have a free mercapto group not forming an alkali metal salt, the compounds of the Formula II are preferred. These compounds have almost equivalent reactivities to the alkali metal salts.

The polyepihalohydrin rubbers to be vulcanized in accordance with the process of the invention are homopolymers of epichlorohydrin or epibromohydrin, and copolymers of epihalohydrins and copolymerizable monomers. Examples of the copolymerizable monomers are epoxides such as ethylene oxide, propylene oxide, butylene oxide, butadiene monoxide, cyclohexene oxide, ethyl glycidyl ether, allyl glyceridyl ether, tetrahydrofuran or trioxane; isocyanates such as ethyl isocyanate, phenyl isocyanate, or 2,4-tolylene diisocyanate; alkyl acrylates such as ethyl acrylate or methyl methacrylate; vinyl ketones such as methyl vinyl ketone or cyclohexyl vinyl ketone; cyclic acid anhydrides such as maleic anhydrides, succinic anhydride, or phthalic anhydride; diolefins such as butadiene, isoprene, or pentadiene; monoolefins such as ethyl ene, propylene, or butene-l; nitrile compounds such as acryloni-trile or methacrylonitrile; and butylene. Furthermore, kneaded mixtures of these polymers with diene-type rubbers or chlorinated rubbers may also be used. In other words, the process of the present invention is applicable to any polymer which substantially contains an epihalohydrin.

The amount of trithiocyanuric acid or its derivative used in the invention is usually from 0.5 to 5 parts by weight per 100 parts by weight of the polyepihalohydrin rubber. But amounts in excess of 5 parts by weight may also be employed without any appreciable trouble since if being present in the vulcanized product in the unreacted state, this compound also acts effectively as an antioxidant.

A first embodiment of the process of the invention is performed by heating the polyepihalohydrin rubber in the presence of trithiocyanuric acid and/ or its derivative described above. In Order to enhance the cross-linking reactivity further, the heating may be eiiected in the copresence of a vulcanization accelerator or vulcanization assistant. Suitable examples of the vulcanization accelerator or assistant include alkali metal salts or alkaline earth metal salts of aromatic or aliphatic or polybasic acids (for example, benzoic acid, phthalic acid, acetic acid, stearic acid, adipic acid, or azelaic acid); alkali metal salts of cyanuric acid; oxides, hydroxides, sulfides, carbonates, or phosphates of alkali metals or alkaline earth metals; thioacid salts such as sodium ethylxanthate; dithioacid salts such as sodium dithiocarbamate, sodium dimethyldithiocarbamate, or piperidine-pentamethylene dithiocarbamate; thiazoles such as Z-mercaptobenzothiazole, dibenzothiazyl sulfide, or N-cyclohexylbenzothiazyl sulphenarnide; Z-mercaptothiazoline; 2-mercaptobenzimidazole; urea derivatives such as ethylene urea or diphenyl urea; thiourea derivatives such as triethyl thiourea, diphenyl thiourea, tributyl thiourea, tetraethyl thiourea, or thiocarbanilide; guanidine derivatives such as diphenyl gaunidine; thiuram compounds such as tetramethyl thiuram monoor disulfide; and sulfur and monoaminies or polyamines such as laurylamine, hexamethylene diamine, piperazine, or melamine. Sulfur is especially preferred. These compounds are used either alone or in admixture of two or more. The amount of the vulcanization assistant or accelerator used is from 0 to 10 parts by Weight per 100 parts by weight of the polyepihalohydrin rubber.

In a second embodiment of the process of the invention, the vulcanization of the polyepihalohydrin rubber is performed in the presence of (a) trithiocyanuric acid or its derivative described above and (b) a 2-mercaptoimidazoline or a carbamate of a polyamine. The conjoint use of the compound (b) is designed to enhance the cross linking reactivity. Typical examples f he Z-m P imidazoline include Z-mercaptoimidazoline, 4-methyl-2- mercaptoimidazoline and 5-ethyl-4-butyl-2-mercaptoimidazoline. Examples of the carbamate of a polyamine are hexamethylenediamine carbamate and ethylenediamine carbamate. The compound (b) is already known as one component of a vulcanizing agent for polyepihalohydrin rubbers. It however acts efiectively as an accelerator for compound (a) in the present invention even in so small an amount which would not fully prove eifective when used in accordance with the known methods. The use of the compound (b) together with the compound (a) leads to vulcanized products of very superior resistance to aging under heat. The amount of the compound (b) used is from 0.1 to 10 parts by weight per parts by weight of the polyepihalohydrin rubber.

The other conditions applicable to the case of using the compound (b) conjointly are the same as those hereinabove described.

Asis demonstrated by Examples 40 and 43 for instance, the vulcanized polyepihalohydrin rubbers obtained by the process of the present invention hardly undergo a reduction in strength even by heat aging at C. for 20 days, and possess excellent resistance to aging under heat which cannot be seen in polyepihalohydrin rubber vulcanizates having a cross-linked chain such as monosulfide, disulfide, or alkylene that have generally been known heretofore. These properties are considered to be exhibited by the following factors (1) to (4).

(1) Stabilization of the cross-linked chain by a large resonance energy possessed by the s-triazine ring.

(2) Powerful insulating effect of the cross-linked chain (trithiocyanuric acid ring) against the inducing action of the main chain molecules between the cross-linked chains which action accelerates thermal decomposition.

(3) Steric hindrance effect of the s-triazine ring at the time of forming a sulfonium salt with the sulfide linkage which induces the activation of the unreacted halogen that becomes a cause of thermal decomposition of the polyepihalohydrin rubber vulcanizate.

(4) The vulcanizing agent itself has an effect of preventing oxidation, and the resultant cross-linked chain assumes a structure similar to that of an alkylthithiocyanuric acid that exhibits good prevention of oxidation and acts as a durable cross-linking stabilizer.

In either the first or second embodiment of the invention, the vulcanization is performed by mixing trithiocyanuric acid and/or its derivative (first embodiment) or compounds (a) and (b) mentioned above (second embodiment) with the polyepihalohydrin rubber together, if desired, with the assistant described above by an ordinary method such as roll mixing, Bumbury mixing, or solution mixing, and then heating the resultant mixture. The vulcanization temperature is usually from 120 C. to 190 C., and the vulcanization time is from about 5 to 120 minutes.

It desired, ordinary chemicals for rubber such as reinforcing agents, fillers, softening agents, plasticizers, antioxidants, stabilizers or activators may be added besides the vulcanizing agents.

The invention will be described specifically by the following examples in which all figures in the compounding recipes are parts by weight.

EXAMPLES 1 TO 5 AND COMPARATIVE EXAMPLE 1 In each run, the ingredients of the recipe shown in Table 1 were kneaded for about 30 minutes at 3040" C. with a 6-inch roll, and then vulcanized at C. for 40 minutes. The physical properties, gell content, and degree of swelling of the vulcanized products obtained were measured both before and after aging under heat. The results are given in Table 2.

TABLE 1 It is clear from the results shown in Table 3 that in Example Example 1611111161 case, a rkedbiiction in strength due to aging under omp. em Compounding recipe 1 2 3 Ex. 1 5 eat was r at a e Polyepichlorohydrin rubber..- 100 100 100 100 100 100 5 EXAMPLE 6 E1325 carbon black 4g 4g 49 4(1) 4( 4( n earate Trithiocyanurlc acid..- 1 1.5 2 0.5 1 A vulcanrzate of polyeprchlorohydrm rubber was pre- 1 1 figgg ifg fig gffii; o 2 0 2 0 2 1 Z 5 5 pared in the same way as set forth In Example 3 except Hydrin 100 (trade name, Goodrich Company: this applies to all of the 3 parts by .welght of 2'pheny1'46dlmercapto's'tn Pmyepwhbmhydri rubbers used the examples) azme was used instead of 2 parts by weight of trithio- TABLE 2 Example 1 Example 2 Example 3 150 C. 150 C. 150 C After After After After After After After After After Before 3 12 Before 3 9 20 Before 12 20 Aging conditions aging days days days aging days days days aging days days days Strength at break (kg/cm!) 126 159 1 8 87 137 153 152 121 137 158 149 135 Elongation at break (percent).. 348 270 270 253 217 162 165 150 150 115 105 120 100% modulus (kg/cm?) 46 63 53 36 80 95 104 140 145 12g 200% modulus (kg/cmfi). 96 136 106 72 132 Hardness (Shore A) 68 73 70 64 77 80 81 82 32 33 Gell content (percent) 99. 3 98. 1 93. 4 90. 0 98. 9 94. 0 100 99. 4 97.4 94. 2 Degree of swelling (percent) 290 286 345 365 240 256 222 229 229 244 Comparative Example 1 Example 4 Example 5 After After After After After After After After After Before 3 12 20 Before 3 6 9 12 Before 3 6 Aging onditions aging days days days aging days days days days aging days days Stren h at break (k .lcm!) 119 148 90 153 160 146 121 108 130 135 12s Elongation at break %percent)- 533 290 300 320 250 190 190 195 200 190 100 126 100% modulus (kg. cm?) 34 69 27 83 80 60 60 135 120 200% modulus (kg/cm!) 68 128 40 Hardness (Shore A) 66 74- 72 63 75 78 77 74 74 76 81 80 Gell content (percent) 98. 9 98. 2 87. 0 80. 7 Degree of swelling (percent) 338 299 388 478 Tested after immersion in tetrahydrofuran for 48 hours (this equally applies to the following examples).

It is seen from the results of strength at break in Table 2 that by the present invention, excellent vulcanized products of polyepihalohydrin rubbers which can fully endure aging under heat for prolonged periods of time can be obtained. Even in a small amount, the Z-mercaptoimidazoline clearly exhibits its effect. On the other hand, when trithiocyanuric acid is not used as in Comparative Example 1, the vulcanizate sufiers from a marked reduction in strength due to aging under heat.

COMPARATIVE EXAMPLES 2 TO 4 Using the typical conventional vulcanizing agents, the ingredients were kneaded and vulcanized in the same way as set forth in Example 1. The physical properties, gell content, and degree of swelling of the vulcanizates were measured both before and after aging under heat. The compounding recipe and the results of measurement are given in Table 3.

cyanuric acid. The heat aging test was conducted at 150 C. The results are shown in Table 4.

A vulcanizate of polyepichlorohydrin rubber was prepared in the same way as set forth in Example 1 except that 2 parts by weight of sodium adipate was further TABLE 3 Comparative Example 2 Comparative Example 3 Comparative Example 4 Compound recipe:

Polyepichlorohydrin rubber..." 100 100 FEF carbon black 40 40 40 Tin stearate 1 1 1 Trithlocyannrlc acid r 2 mercaptoimidazoline 1. 5 1 1 Red lead 5 5 5 Aging conditions Before After After After Before After After After After Before After After After After aging 12 20 aging 3 6 9 12 aging 3 6 9 12 days days days days days days days days days days days Physical properties:

Strength at break (lcmJcmJL... 142 173 77 32 159 173 121 67 26 134 141 41 13 9 Elongation at break (percent)..- 405 233 300 315 520 280 275 310 320 532 258 300 293 214 100% modulus (kg./cm.=) 45 80 36 19 38 63 15 39 49 19 10 8 200% modulus (kgJcmfl). 126 61 28 -107 Hardness (Shore A)-.-- 71 71 69 60 64 73 71 62 54 70 76 60 55 35 Gell content (percent) 100 98. 7 87. 7 81. 8 97. 7 95. 6 79. 9 Degree of swelling (percent) 263 248 363 401 308 269 372 8 EXAMPLES 9 TO 12 Each of the compound mixtures shown in Table 7 TABLE below containing trithiocyanuric acid and hexarnethylene- Aging conditions 5 diamine carbamate was vulcanized at 160 C. for After After After After minutes. The results of the heat aging test (at 160 C.) Before 3 6 9 12 Physical properties aging days days days days of the vullcanlzatges erg sholwn 1n Table 7 also. In any an' o c vin exce en re istanc t0 Strength at break (kg./en1. 113 149 146 130 103 a W c 126 pr u t a g t S e Elongation at break (percent) 320 127 150 137 133 10 aging under heat could be obtained. The use of the antr- 100% modulus (kg/cm!) 56 97 107 99 73 200% modulus (kg./crn. 11s oxidant comorntly can further increase the strength at Hardness (Shore A) 81 81 80 Gell content (percent) 97 98.5 97.7 95.5 94. 0 break of the vulcanized products. Degree of swelling (pereen 264 223 228 227 749 TABLE 7 Example 9 Example 10 Example 11 Example 12 Compounding recipe:

olyepichlorohydrin-..- 100 100 100 100 FEF carbon black 40 40 40 40 Tim sfpqmte 1 1 2 2 Trithiocyanuric acid 1. 5 2 2 2 Hexamethylene diamine carbamate 0. 5 1 1 1 Magnesium oxide 5 5 5 5 Sulfur 1 N iekel dibutyl dithiocarhmn am 0. 5 0. 5 Phenyl-3-naphthylaminn 1 1 Number of days for aging 0 3 6 9 12 0 3 6 9 12 0 3 6 9 l2 0 3 6 9 12 Properties of the vulcanized product:

Strength at break (kgJc-mfi)- 138 121 107 141 127 136 117 105 Elongation at break (percent) 110 110 100 184 100 100 97 100 100% modulus (kg/em!) 128 100 200% modulus (kg/cm) 300% modulus (kgJcmfl 1 Hardness (Shore A) 87 86 81 EXAMPLE 8 A vulcanizate of polyepichlorohydrin was prepared in the same was as set forth in Example 7 except that 3 parts by weight of 2-diphenylamino-4,6-dimercapto-s-triazine was used instead of 1.5 parts by weight of trithiocyanuric acid. The vulcanizate obtained was tested at 160 C. as to its aging stability under heat. The results are shown in Table 6.

EXAMPLES 13 TO 23 AND COMPARATIVE EXAMPLE 5 In each run, a mixture of polyepichlorohydrin rubber with trithiocyanuric acid and Z-rnercaproimidazoline and TABLE 5 various assistants was vulcamzed at 160 C. for 40 mln- Aging conditions utes, and the physical properties of the resulting vulcan- 45 After After After After izate were measured. The compound rec pes and the re Before a 6 9 2 sults obtained are shown in Table 8. It 1s seen from the Physmal pmpmtes agmg days days days days results that good vulcanized products of the polyepichloro- Strength at break (kg./cm. 117 138 127 109 97 hydrm rubber were obtained. Elongation at break (percent). 268 148 195 163 160 100% modulus (kgJemfi) 63 78 73 65 200% modulus (kg/0111. 108 9 Hardness (Shore A) 76 78 78 75 72 Gell content (percent).-- 98. 5 99. 1 97. 4 94. 8 93. 0 Degree of swelling (percen 256 234 240 250 281 TABLE 8 Comp. Example N umber 13 14 15 16 17 18 19 20 21 22 23 Ex. 6

Compounding recipe:

Polyepichlorohydrin rubber 100 100 100 100 100 100 100 100 100 100 100 FEF carbon black 40 40 40 40 40 40 40 40 40 40 40 40 Tin stearate 1 1 1 1 1 1 1 1 1 1 1 1 Trithiocyanuric aeid 2 2 2 2 2 2 2 2 2 2 2 2-mereaptoimidazoline. 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 Magnesium oxide--- 2 5 5 3' Sodium sehamte 1 1 Sulfur 1 0. 5 Lead sulfide 5 Basie lead carhnnate 5 Barium oxide--- 5 Calcium oxide--- 5 Barium ulfide 5 Calcium hydroxide 5 Calcium hydroxide Barium carb are 5 Red lead 5 Ph 2 meircaptobtenziuf1itdazglt a "dug sica r0 er ms 0 1e c r0 uc strength ht break (kg./em. 113 140 145 141 123 120 105 93 Elongation at break (percent 500 270 310 210 370 380 400 180 500 170 650 100% modulus (kg. /cm. 39 58 76 86 47 46 45 74 41 90 103 51 300% modulus (kgJcrnfi) 95 114 141 113 110 100 72 67 Hardness (Shore A) 70 74 79 77 70 68 76 78 72 76 78 1 1 1 2 Although it is not essential to use an antioxidant in the It is seen from the results shown in Table 14 that the present invention, the use of an antioxidant is effective vulcanized products obtained by the invention have good for retaining good strength even after aging for prolonged physical properties. As is seen especially from the results periods of time, as is seen from Table 12. of the strength at break and gell content, the vulcanizates TABLE 12 Example 34 Example 35 Number of days for aging 3 6 9 12 0 3 6 9 12 Physical properties of the vulcanized product:

Strength at-break (kg/cm?) 136 153 13s s 81 153 154 140 125 109 Elongation at break (percent) 150 123 120 120 108 140 100 89 87 87 100% modulus (kg/cm!) 105 146 124 105 140 Hardness (Shore A) 81 83 84 84 83 83 85 85 86 86 EXAMPLES 36 TO 42 AND COMPARATIVE obtained by the invention can fully endure aging under EXAMPLE 7 heat for prolonged periods of time. Comparative Example 7 shows the results obtained with a typical conven- In each run, the ingredients of the recipe shown in tional vulcanizing agent, from which it is seen that the Table 13 were kneaded for about minutes at 30-40 vulcanizate aged for more than 12 days exhibits a marked (3., and then vulcanized at 160 C. for minutes. The reduction in Strength and ge 11 coflteni, Showing a tendency physical properties, gel content, and degree of swelling toward Softemng and detenorauon' of the resulting vulcanizates were measured before and 25 EXAMPLES 3 TO 48 A vulcanized polyepichlorohydrin rubber was prepared from the compounding recipe shown in Table 15 in which TABLE 13 Example Comp. Compounding recipe 36 37 38 39 40 41 42 Ex.7

Polyepiohlorohydrinrubber 100 100 100 100 100 100 100 10 FEB carbon black. 0 4 40 Tin stem-ate Trithioeyanm'lc acid Sodium trithioeyamrram 2diphenylarnino-4fi-dimercapto-sfi z-diphenylamino-tmiimercapto-stliaziue sodium salt 2-phenoxy-4,6-dimereapt0-s-triazine 2-ethoxy-4,6-dimercaptos-triazine Magnesium oxide. 5 5 5 Sodium adipate.-. 5

2-mereaptoimidazoline. Red lead after aging at 150 C. The results are shown in Table the amount of trithiocyanuric acid was decreased as com- 14, pared with Example 38 and a vulcanization accelerator TABLE 14 Example 36 Example 37 Example 38 After After After After After After After After After Aging cnnrlitirms Before 3 12 20 Before 3 12 20 Before 3 12 20 aging days days days aging days days days aging days days days Strength at break (kg. lcmfi) 120 166 140 115 110 150 120 84 106 90 58 57 Elongation at break (percent) 350 149 117 110 370 284 275 295 493 160 80 100 100% modulus (kg/om!) 58 125 135 106 48 60 48 43 57 300% modulus (kg. /em. 11'! 106 B 125 I 100 5 77 88 Hardness (Shore A)--- 74 82 85 84 73 78 78 76 72 83 87 84 Gell content (percent) 98 1 100 98. 8 97. 9 100 99. 4 96. 4 92. 8 96. 0 98. 0 97. 0 93. 5 Degree of swelling (percent 277 236 220 224 276 279 307 342 450 296 269 270 Example 39 Example 40 Example 41 After After After After After After After After After Aging nnnr'iitinns Before 3 12 20 B81018 3 12 20 Before 3 12 2O aging days days days aging days days days aging days days days Strength at break (kg/em?) 130 151 79 118 160 150 121 116 143 131 117 Elongation at break (percent) 567 383 370 360 316 273 280 280 165 140 120 140 100% modulus (kg/em?) 45 50 52 35 48 65 55 40 88 124 117 104 300% modulus (kg/cm!) 100 112 80 116 a 130 I 120 9 90 Hardness (Shore A) 70 76 76 71 70 74 73 65 81 85 84 83 Gell content (percent). 99. 8 98. 0 94 8 90. 6 100 99. 4 97.7 95. 4 100 100 98. 9 97.4 Degree of swelling (percent)- 326 304 353 408 282 273 311 310 403 224 227 241 Example 42 Comparative Example 7 Aging onndifinn Before After 3 After 12 After 20 Before After 3 After 12 After 20 aging days days days aging days days days Strength at break (kg-Inn?) 109 133 128 109 142 173 77 32 Elongation at break (percent)- 191 133 140 405 233 300 315 100% modulus (kg-lam?) 70 114 111 90 45 80 36 19 300% modulus (kg/cm?) 126 l a 61 28 Hardness (Shore A) 79 82 83 79 71 77 69 61 Gell content (percent) 100 100 99. 9 97. 4 100 98. 7 87. 7 81. 8 Degree of swelling (percent) 236 222 227 245 263 248 363 400 l 200% modulus.

shown m Table was used congomtly. The physical were measured. The results obtained are shown in properties of the vulcamzed product were measured both Table 17.

, TABLE 17 Example Compounding recipe:

Polyepichlorohydrln rubber 100 100 100 100 100 100 100 100 100 100 100 100 100 FEF carbon black 40 40 40 40 40 40 40 40 40 40 40 40 40 Tin stearate 1 1 1 1 1 1 1 1 1 1 1 1 1 'Irithiocyanurlc acid- 4 2 2 1. 5 2 2 1. 5 1. 5 1. 5 1. 5 2 2 2 Magnesium oxide- 5 5 5 5 5 5 5 5 5 5 Sodium methylate 1 Potassium acetate 5 Potassium cyanurate 5 Sodium diethyldithiocar m ate 1. 7 Sulfur 0. 5 Trimethylthio 0. 5 Ethyleneurea- 2 N ,N'-dipheny1urea 0. 5 1,3-djpheny1 gnnnirlinn O, 5 Cyclohexylbenzothiazyl nlnh mi 0. 5 Melamine 0, 5 Laurylamine 5 Piperazine. 0. 5 Acting B e 0. 5 Properties of the vulcanized product:

Strength at break (kgJcmfi) 100 107 104 123 110 112 103 112 118 119 126 135 130 500 265 520 220 420 270 540 340 570 310 400 260 210 36 46 35 72 40 70 52 55 32 48 45 61 83 b 89 80 95 90 109 85 112 113 b 120 Hardness (Shore A) 71 68 70 83 8O 75 70 76 71 75 e Tradename for polyamine, Yoshitomi Pharmaceutical 00., Ltd. 11 200% modulus.

before and after aging at 150 C. in the same way as in Example 36. The results are shown in Table 16.

TABLE 15 30 EXAMPLES 62 TO 65 AND COMPARATIVE Example EXAMPLE 8 Compounding recipe 43 44 45 46 47 48 P 1 m h dfi NJ 100 100 100 100 100 100 The ingredients of the recipe shown m Table 18 were 0 e 1e oro n ru er Full arbon bl ck 46 4o 40 40 40 4o kneaded and vulcanized m the same way as set forth 1n 1 1 1 gifi gigfifijfgg ii 5 2 2 2 35 Example 36. The aging test was conducted at 160 C. The 933 5333..331 f results are shown in Table 19 together with the results of Tetramethyl thiuram d1sulfide- 0. 5 1 2-mercaptobenzimidazole Potassium xnnthmmnate 1 40 TABLE 16 Example 43 mp 44 Example 45 After After After After After After After After After Before 3 9 20 Before 3 12 20 Before 3 9 20 Aging conditions aging days days days gmg y ays days aging days days days Stren th at break k cm?) 123 167 150 134 130 149 1 0 118 124 160 147 102 Elong ation at brealc %p ercent) 267 215 183 187 157 110 105 115 400 298 289 280 100% modulus (kg/0111. 67 92 79 150 139 53 68 69 48 200% modulud (kgJcmi) 166 93 124 86 Hardness (Shore A) 76 77 80 80 82 84 82 72 73 78 76 Gel content (percent) 99.5 97.8 .8 99.7 97.9 95.3 91.5 99.3 97.3 91.7 Degree of swelling (percent) 247 245 27 8 216 232 271 283 283 311 Example 46 Example 47 Example 48 Before After After After Before After After After Before After Aging conditions aging 3 days 12 days 20 days aging 3 days 12 days 20 days aging 3 days Stren th at break k cm. 119 146 141 111 94 149 135 111 102 Elong ation at breal; %p ercer1t) 245 170 150 575 150 150 558 317 100% modulus (kg/cm!) 77 110 100 8 3 110 100 88 35 65 200% modulus (kg/cm!) B 70 a. 79 Hardness (Shore A) 77 82 82 32 63 76 80 76 67 79 Gel content (percent) 93.5 99.3 95.7 92.2 98.5 98.9 98.7 97.3 99.2 95.3 Degree of swelling (percent) 250 238 275 295 3 279 250 277 380 352 e 300% modulus.

*It is clear by comparison of these examples with Example 38 that by the conjoint use of a vulcanization accelerator, vulcanized products having lesser changes in strength due to aging under heat can be obtained.

EXAMPLES 49 TO 61 In each run, the ingredients of the compounding recipe shown in Table 17 were mixed, and then vulcanized at 160 C. for 40 minutes. The physical properties of the resulting vulcanization product in a normal condition Comparative Example 8 in which a typical conventional vulcanizing agent was used.

Tin stearate Trit hiocyanun'c acid. 2-d1phenylamino-4,6-d1mercap o-s- Magnesium oxide Sodium adipate..

Tn'methyl thiourea. Tetramethyl thiuram isnlfide 0.5 Z-mercaptobenzimidazole Lead red Z-mercaptoimidazoline TABLE 19 Example 62 Example 63 Example 64 After Aiter After After After After After After After After After After Aging conditions Before 3 6 9 12 Before 3 6 9 12 Before 3 6 9 12 aging days days days days aging days days days days aging days days days days Physical properties of the vulcanized product:

Strength at break (kg/cm?) 107 145 128 126 102 105 137 131 128 104 81 137 127 115 108 Elongation at break (percent).-- 280 159 156 166 152 397 165 178 200 163 733 128 128 120 117 100% modulus (kg/cm?) 65 95 89 84 72 41 88 81 74 73 37 115 109 100 95 300% modulus (kg/cm?) 105 90 64 Hardness (Shore A) 76 77 80 79 71 78 77 78 68 83 82 83 83 Gel content (percent) 97. 6 98.0 100 95. 96. 9 98. 1 97. 6 96. 0 94. 9 98. 9 99. 9 97. 6 Degree of swelling (percent) 243 233 228 246 315 235 248 240 456 219 212 219 Example 65 Comparative Example 8 Aging conditions Before After After After After Before After After After aging 3 days 6 days 9 days 12 days aging 3 days 6 days 9 days Physical properties of the vulcanized product:

Strength at break (kg/cm?) 102 123 97 76 51 134 141 41 13 Elongation at break (percent). 492 242 260 267 225 532 258 300 293 100% modulus (kg/0111. 40 60 44 40 31 39 50 19 300% modulus (kg./om. 80 107 Hardness (Shore A) 70 74 72 72 68 70 76 60 55 Gel content (percent) 97. 9 96.8 94. 7 86. 4 97. 7 95. 6 79. 9 65v 5 Degree of swelling (percent) 306 280 290 307 308 269 372 404 aging stability, said process comprising heating said EXAMPLES 66 AND 67 The ingredients of the recipe shown in Table 20 which contained hexamethylenc diamine or piperazine together with trithiocyanuric acid were kneaded, and vulcanized in the same way as set forth in Example 36. The physical properties of the vulcanizates before and after aging at 160 C. were measured. The results are shown in Table 20.

polyepihalohydrin rubber at a temperature of 120 to 190 C. for a period of from 5 to 120 minutes in the presence of at least 0.5 part by weight, per 100 parts by weight of said polyepihalohydrin rubber, of trithiocyanuric acid or a derivative thereof selected TABLE 20 Example 66 Example 67 Compounding receipe:

Polyepichlorohydrin rubber 100 100 FEF carbon black 40 Tin stear 1 1 Trithiooyanuric acid 1 .5 2 Hexamethylene diarnine Pipnrminu 1 Magnesium oxide 5 5 Before After After Before Aft-er After aging 3 days 6 days aging 3 days 6 days Aging conditions Physical properties of the vulcanized product:

Strength at break (kg/em!) 140 93 122 110 Elongation at break (percent)- 380 170 190 370 183 167 modulus (kg/cm?) 57 68 48 63 75 55 300% modulus (kg/cm?) 116 Hardness (Shore A) 77 78 76 84 84 82 Wh we l i i from the group consisting of compounds represented 1. A process for vulcanizing polyepihalohy-drin rubber by the formulae: selected from the group consisting of: 70 s (1) homopolyrners of polyepihalohydrin, and (2) copolymers of epihalohydrin with monomer co- N polymerizable therewith, to produce vulcanized prod- BIS-5Q /C-s R2 ucts having excellent solvent resistance and excellent 75 N C=N N=C AR: AR:

wherein R represents a hydrogen atom or an alkali metal; R represents a hydrogen atom, an alkali metal, an alkyl group of the formula C H or a phenyl group; R represents a hydrogen atom, an alkyl group of the formula C H a phenyl group, a cyclohexyl group, an allyl group or a naphthyl group; R represents a phenyl group, a morpholino, group, a piperazino group or a naphthyl group; Q represents O(C,,H O-,

S(C,,H )S or SCH (CH OCH ),,CH S; n represents a positive integer.

2. The process of claim 1, wherein the amount of the trithiocyanuric acid or said derivative thereof present during said heating is 0.5 to 5 parts by weight per 100 parts by weight of the polyepihalohydrin rubber.

3. The process of claim 1, wherein said polyepihalohydrin rubber is polyepichlorohydrin rubber.

4. The process of claim 1, wherein said polyepihalohydrin rubber is an epichlorohydrin-ethylene oxide or propylene oxide copolymer rubber containing a substantial portion of epichlorohydrin.

5. The process of claim 1, wherein up to parts by Weight, based on 100 parts by weight of the polyepihalohydrin rubber, of a vulcanization assistant is also present during said heating.

6. The process of claim 5 wherein said vulcanization assistant is sulfur.

7. The process of claim 1 wherein said monomer copolymerizable with said polyepihalohydrin is selected from the group consisting of epoxides, isocyanates, alkylacrylates, vinyl ketones, cyclic acid anhydrides, diolefins, monoolefins, nitrile compounds and butylene.

8. The process of claim 5 wherein said vulcanization assistant is selected from the group consisting of alkali metal and alkaline earth metal salts of aromatic, aliphatic or polybasic acids, alkali metal salts of cyanuric acid, oxides, hydroxides, sulfides, carbonates and phosphates of alkali metals and alkaline earth metals, thioacid salts, dithioacid salts, thiazoles, Z-mercaptobenzimidazole, urea compounds, thiourea compounds, guanidine compounds, thiuram compounds, monoamines and polyamines.

9. The process of claim 10 wherein said monomer copolymerizable with said polyepihalohydrin is selected from the group consisting of epoxi-des, isocyanates, alkylacrylates, vinyl ketones, cyclic acid anhydrides, diolefins, monoolefins, nitrile compounds and butylene.

10. A process for vulcanizing polyepihalohydrin rubber selected from the group consisting of:

(1) homopolymers or polyepihalohydrin, and

(2) copolymers of epihalohydrin with monomers copolymerizable therewith, to produce vulcanized products having excellent solvent resistance and excellent aging stability, said process comprising heating said polyepihalohydrin rubber at a temperature of 120 to 190 C. for a period of from 5 to 120 minutes in the presence of (a) at least 0.5 part by weight per 100 parts by weight of said polyepihalohydrin rubber, of trithiocyanuric acid or a derivative thereof selected from the group consisting of the compounds repersented by the formulae:

wherein R represents a hydrogen atom or an alkali metal; R represents a hydrogen atom, an alkali metal, an alkyl group of the formula C H or a phenyl group; R represents a hydrogen atom, an alkyl group of the formula C H a phenyl group, a cyclohexyl group, an allyl group or a naphthyl group; R represents a phenyl group, a morpholino group, a piperazino group or a naphthyl group; Q represents -O(C,,H ,,)O,

OCH (CH OCH CHO,

represents a positive integer; and also in the pres ence of (b) from 0.1 to 10 parts by weight per 100 parts by weight of said polyepihalohydrin rubber, of

a Z-mercaptoimidazoline or a carbamate of a polyamine.

11. The process of claim 10, wherein the amount of compound (a) present during said heating is 0.5 to 5 parts by weight per parts by weight of the polyepihalohy- 19 drin rubber copolymer, and the amount of compound (b) is 0.1 to 10 parts by weight per 100 parts by weight of the epihalohydrin homopolymer or copolymer.

12. The process of claim 10, wherein up to 10 parts by weight, based on 100 parts by weight of the polyepihalohydrin rubber of a vulcanization assistant is also present during said heating.

13. The process of claim 10, wherein said polyepihalohydn'n rubber is polyepiehlorohydrin rubber.

14. The process of claim 10, wherein said polyepihalohydrin rubber is an epichlorohyrin-ethylene oxide or propylene oxide copolymer rubber containing a substantial portion of epihalohydrin.

15. The process of claim 10, wherein said compound (b) is Z-mercaptoimidazoline.

16. The process of claim 10, wherein said compound (b) is hexamethylenediamine carbamate.

17. The process of claim 12 wherein said vulcanization assistant is selected from the group consisting of alkali metal and alkaline earth metal salts of aromatic, aliphatic or polybasic acids, alkali metal salts of cyanuric acid, oxides, hydroxides, sulfides, carbonates and phosphates of alkali metals and alkaline earth metals, thioacid salts, dithioacid salts, thiazoles, Z-mercaptobenzimidazole, urea compounds, thiourea compounds, guanidine compounds, thiuram compounds, monoamines and polyamines.

References Cited UNITED STATES PATENTS 3,341,491 9/1967 Robinson et a1. 260-4575 3,366,598 1/ 1968 Westlinning et a1. 260-415 3,341,475 9/ 1967 Vandenberg 2602 3,240,749 3/1966 Dexter 26045.8

DONALD E. CZAIA, Primary Examiner M. I. MARQUIS, Assistant Examiner US. Cl. X.R.

2602 A, 37 EP, 41 R, 45.8 NT, 77.5 A, 79.5 C, 88.3 A 

